GANCICLOVIR
Clinical safety rating: avoid
Contraindicated (not allowed)
Ganciclovir is a synthetic guanine nucleoside analog that inhibits viral DNA synthesis by competitively inhibiting viral DNA polymerase and by incorporating into viral DNA, causing chain termination. It requires initial phosphorylation by viral thymidine kinase (CMV) or protein kinase (HSV).
| Metabolism | Ganciclovir is not significantly metabolized; it is primarily excreted unchanged by the kidneys via glomerular filtration and active tubular secretion. Less than 1% is metabolized to 9-[(1,3-dihydroxy-2-propoxymethyl)guanine]. |
| Excretion | Renal excretion: >90% unchanged; biliary/fecal: minimal (<5%) |
| Half-life | Terminal half-life: 2.5-5.0 hours in normal renal function; prolonged to 10-30 hours in renal impairment; requires dose adjustment for CrCl <70 mL/min |
| Protein binding | 1-2% bound; primarily to albumin (low binding) |
| Volume of Distribution | 0.47-0.74 L/kg; indicates extensive distribution into tissues including brain, eye, and lungs |
| Bioavailability | Oral: 6-9% (fasting); increased to 30% with food due to enhanced absorption |
| Onset of Action | IV: rapid, within 24-48 hours; oral: slower, onset within 3-5 days due to low bioavailability |
| Duration of Action | Dosing interval-dependent; with normal renal function, duration of antiviral effect is approximately 12 hours; requires twice-daily IV dosing for continuous suppression |
Induction: 5 mg/kg IV every 12 hours for 14-21 days. Maintenance: 5 mg/kg IV every 24 hours. Oral: 1000 mg three times daily with food.
| Dosage form | CAPSULE |
| Renal impairment | CrCl ≥70 mL/min: 5 mg/kg q12h (induction), 5 mg/kg q24h (maintenance); CrCl 50-69: 2.5 mg/kg q12h, then 2.5 mg/kg q24h; CrCl 25-49: 2.5 mg/kg q24h, then 1.25 mg/kg q24h; CrCl 10-24: 1.25 mg/kg q24h, then 0.625 mg/kg q24h; CrCl <10: 1.25 mg/kg 3 times/week after hemodialysis. Oral: CrCl ≥70: 1000 mg tid; 50-69: 1500 mg qd or 500 mg tid; 25-49: 1000 mg qd or 500 mg bid; 10-24: 500 mg qd; <10: 500 mg 3 times/week after dialysis. |
| Liver impairment | No dose adjustment required for hepatic impairment. Use with caution in severe hepatic dysfunction due to limited data. |
| Pediatric use | Induction: 5 mg/kg IV every 12 hours for 14-21 days. Maintenance: 5 mg/kg IV every 24 hours. Oral dosing in children ≥9 years: 1000 mg three times daily with food; for children <9 years, use weight-based: 30 mg/kg per dose (max 1000 mg) three times daily. |
| Geriatric use | No specific dose adjustments beyond renal function. Closely monitor renal function and adjust dose based on CrCl. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other bone marrow suppressants may have additive effects Can cause severe myelosuppression and mutagenesis.
| Breastfeeding | Not recommended. M/P ratio unknown; ganciclovir is excreted into breast milk in rats. Potential for severe adverse effects in nursing infant (e.g., bone marrow suppression, carcinogenesis). |
| Teratogenic Risk | FDA Pregnancy Category B. Animal studies show teratogenicity (e.g., cleft palate, anophthalmia) at doses near human exposure. Human data limited; avoid first trimester unless benefit outweighs risk. Second/third trimester: potential for bone marrow suppression and nephrotoxicity in fetus; use only if clearly needed. |
■ FDA Black Box Warning
Ganciclovir is associated with granulocytopenia, anemia, and thrombocytopenia. Animal studies have shown that ganciclovir is carcinogenic, mutagenic, and causes impairment of fertility and teratogenicity. It is indicated only for the treatment of CMV retinitis and prevention of CMV disease in transplant recipients. Not approved for congenital or neonatal CMV disease.
| Common Effects | Myelosuppression |
| Serious Effects |
["Hypersensitivity to ganciclovir, valganciclovir, or any component of the formulation.","Absolute neutrophil count < 500 cells/μL, platelet count < 25,000/μL, or hemoglobin < 8 g/dL (relative contraindication due to risk of worsening cytopenias).","Pregnancy (avoid unless potential benefit outweighs risk; embryotoxic in animals)."]
| Precautions | ["Hematologic toxicity: Severe leukopenia, neutropenia, anemia, thrombocytopenia, pancytopenia, and bone marrow suppression, especially in patients with pre-existing cytopenias or on concomitant myelosuppressive drugs.","Renal impairment: Dose adjustment required; increased risk of toxicity in renal dysfunction.","Carcinogenicity and mutagenicity: Anticipated in humans based on animal data.","Teratogenicity: Embryotoxic and teratogenic in animals; use only if benefit outweighs risk.","Interaction with mycophenolate mofetil: May increase risk of hematologic toxicity.","Electrolyte disturbances: May cause hypocalcemia, hypokalemia, hyponatremia.","Ocular effects: Retinal detachment in patients with CMV retinitis (not directly drug-related).","Seizures and neurotoxicity: Rare, especially in patients with CNS conditions or renal impairment."] |
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| Fetal Monitoring |
| Monitor CBC with differential and platelets weekly, serum creatinine every 1-2 weeks. Observe for fetal growth restriction and oligohydramnios via ultrasound. Monitor for maternal neutropenia, thrombocytopenia, and renal impairment. |
| Fertility Effects | Animal studies: ganciclovir caused reduced fertility in male mice (testicular atrophy, aspermia) and female rats (reduced implantation). Human data limited; may impair spermatogenesis and cause reversible or permanent infertility. |